[commands] Add GroupCog.group_extras to set Group.extras

Co-authored-by: Danny <[email protected]>

discord/ext/commands/cog.py

@@ -145,6 +145,12 @@ class CogMeta(type):
         than :class:`str`. Defaults to ``True``.
 
         .. versionadded:: 2.0
+    group_extras: :class:`dict`
+        A dictionary that can be used to store extraneous data.
+        This is only applicable for :class:`GroupCog` instances.
+        The library will not touch any values or keys within this dictionary.
+
+        .. versionadded:: 2.1
     """
 
     __cog_name__: str
@@ -153,6 +159,7 @@ class CogMeta(type):
     __cog_group_description__: Union[str, app_commands.locale_str]
     __cog_group_nsfw__: bool
     __cog_group_auto_locale_strings__: bool
+    __cog_group_extras__: Dict[Any, Any]
     __cog_settings__: Dict[str, Any]
     __cog_commands__: List[Command[Any, ..., Any]]
     __cog_app_commands__: List[Union[app_commands.Group, app_commands.Command[Any, ..., Any]]]
@@ -183,6 +190,7 @@ class CogMeta(type):
         attrs['__cog_group_name__'] = group_name
         attrs['__cog_group_nsfw__'] = kwargs.pop('group_nsfw', False)
         attrs['__cog_group_auto_locale_strings__'] = kwargs.pop('group_auto_locale_strings', True)
+        attrs['__cog_group_extras__'] = kwargs.pop('group_extras', {})
 
         description = kwargs.pop('description', None)
         if description is None:
@@ -306,6 +314,7 @@ class Cog(metaclass=CogMeta):
                 guild_ids=getattr(cls, '__discord_app_commands_default_guilds__', None),
                 guild_only=getattr(cls, '__discord_app_commands_guild_only__', False),
                 default_permissions=getattr(cls, '__discord_app_commands_default_permissions__', None),
+                extras=cls.__cog_group_extras__,
             )
         else:
             group = None